Dewaxing hydrocarbon oil



Patent ed June 4, 1935 UNITED STATES PATENT OFFICE 2,003,667 DEWAXING HYDROCABBON on.

tion of Delaware No Drawing. Application November 3, 1933, Serial No. 696,535

7 Claim.

This invention relates to dewaxing hydrocarbon oil, and more particularly to the removal of wax from mineral lubricating oil for the production of low pour test lubricating oils.

The invention contemplates a solvent dewaxing process wherein a solvent of the character of a cyclic ketone, such as cyclohexanone is used. Cyclohexanone, for example, is a compoundwhich has the following chemical structure:

CHrOHg-CH:

O 3-CH3-C The invention comprises mixing the wax-bearing oil with a solvent of this type, then chilling to precipitate the wax constituents, and removing the thus precipitated wax from the cold mixture by the usual methods.

I have found that cyclohexanone possesses unexpected advantages as a dewaxing solvent. When dewaxing oil with this solvent, the resulting dewaxed oil has a pour point and solid point substantially below the temperature at which the wax was separated from the oil. This is particularly advantageous in commercial dewaxing operations because it permits obtaining oils of desired low pour test without chilling to as low a temperature as is necessary when dewaxing with the'more commonly known solvents of the prior art.

In order to more clearly describe the invention, I will refer to the following experiments in which a wax-bearing distillate derived from Mid-Continent crude and having a pour point of around 105 F. was dewaxed .by means of cyclohexanone. One volume of this wax-bearing distillate was mixed with about two volumes of cyclohexanone and cooled to 12 F. to precipitate the wax constituents. The cold mixture, containing the precipitated wax, was then filtered in order. to sep- 40 arate the precipitated wax and produce a dewaxed filtrate. The solvent was removed from this dewaxed filtrate by vacuum distillation. The

resulting dewaxed oil from which the solvent was may be used. Thus, it is contemplated that the lower members of the series, such as cyclobutanone, may be used as well as those members of the series having a greater number of carbon atoms up to cyclo-octanone.

The foregoing solvents may advantageously be employed in combination with other solvent liquids which are adapted to serve as diluents and thus substantially reduce the viscosity of the mixture of wax-bearing oil and solvent. The reduction in viscosity of the mixture facilitates precipitation and separation of the wax from the solution, particularly at low temperatures.

As suitable diluent solvents, I contemplate using solvents of the character of benzol or its homologs, or light petroleum fractions, such as propane, butane, and natural gasoline hydrocarbons.

Separationof the precipitated wax from the cold solution may be effected by settling or centrifuging, as well as by filtering.

The solvent of my invention may be adapted to the separation of wax from crude petroleum or from either residual or distillate fractions thereof. It may also be adapted to the treatment of wax concentrates, such as petrolatum for example, for the purpose of effecting separation between the wax and oil constituents.

Obviously, many modifications and variations of the invention, as hereinbefore set'forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. The method of dewaxing wax-bearing mineral 011 comprising mixing theoil with a solvent liquid selected from the group consisting of the cyclic ketones containing from four to about seven carbon atoms, in such proportion that at temperatures of around 0 F., the liquid constituents of the oil are substantially completely soluble, and the solid constituents are substan-' tially insoluble in the mixture, chilling the mixture to a temperature at which the wax is precipitated, removing the thus precipitated wax, and recovering the solvent from the resulting dewaxed oil.

2. The method of dewaxing wax-bearing mineral oil comprising mixing the oil with cyclohexanone in such proportion that upon chilling to precipitate the wax and separating the thus precipitated wax, the resulting dewaxed oil will have a pour test substantially below the temperature of chilling and wax removal, chilling the mixture to around 0 F. to precipitate the wax, removing the wax thus precipitated, and recovering the solvent from the resulting dewaxed oil thereby producing an oil having a pour test substantially below 0 F.

3. The method 0! dewaxing wax-bearing mineral oil comprising mixing the oil with cyclohexanone in such proportion that at temperatures of around 0 I"., the liquid constituents of the oil are substantially completely soluble, and the solid constituents are substantially insoluble in the mixture, chilling themixture to a temperature at which the wax is precipitated, removing the thus precipitated wax, and recovering the solvent from the resulting dewaxed oil.

4. The method of dewaxing wax-bearing mineral oil comprising mixing with the oil a solvent containing cyclohexanone in such proportion that at temperatures or around 0 F., the liquid constituents of the oil are substantially completely soluble, and the solid constituents are substantially insoluble in the mixture, chilling the mixture to a temperature at which the wax is precipitated, removing the thus precipitated wax, and recovering the solvent from the resulting dewaxed oil.

5. The method of dewaxing wax-bearing mineral oil comprising mixing the oil with a diluent of the character of propane to thereby reduce its viscosity, mixing therewith cyclohexanone in such proportion that at temperatures or around 0 F., the liquid constituents of the oil are substantially completely soluble, and the solid constituents are substantially insoluble in the mixture, chilling the mixture to a temperature at which the wax is precipitated, removing the thus precipitated wax, and recovering the solvent from the resulting dewaxed oil.

6. The method of dewaxing wax-bearing mineral oil comprising'mixing the oil with a diluent material adapted to produce a'mixture having a relatively low viscosity at temperatures of around 0 F. and thereby facilitate precipitation of the solid hydrocarbons, mixing therewith cyclohexanone in such proportion that at temperatures of around 0 F., the liquid constituents of the oil are substantially completely soluble, and the solid constituents are substantially insoluble in the mixture, chilling the mixture to a temperature at which the wax is precipitated, removing the thus precipitated wax, and recovering the solvent from the resulting dewaxed oil.

'7. The method of dewaxing wax-bearing mineral oil comprising mixing with the oil a solvent mixture composed of cyclohexanone andvbenzene in such proportions that at temperatures of around 0 F., the liquid constituents of the oil are substantially completely soluble, and the solid constituents are substantially insoluble in the mixture, chilling the mixture to a temperature at which the wax is precipitated, removing the thus precipitated wax, and recovering the solvent from the resulting dewaxed oil.

ERNEST F. PEVERE. 

